Hurricane windows are manufactured with durable hardware, heavy duty frames and impact glass which are all held in place by a super strong adhesive. When you go shopping for storm tight windows, you will notice that all of the best quality ones all have a rating for design pressure. They have to undergo a serious design pressure test, where they simulate hurricane conditions to see how the windows and doors hold up, once they have passed this test, then they qualify for the rating. The test focuses on 3 areas, water pressure, wind pressure and the structural components.
The first test that they do is air filtration, where they are able to measure the amount of wind pressure that the window can withstand without breaking. They then proceed to do the water penetration test, what they are measuring here is the quantity of rainwater that is able to not penetrate the window based on the design pressure rating, they figure out what the water penetration level should be based on a percentage of the design pressure.
Last, but not least is the structural test, what the focus of this test is the upgraded frame and the glass panes. A few ways that the window manufacturers are able to increase their pressure ratings is by using the highest quality of window installation hardware and also by using thicker panes of glass. The pressure level that you see indicated in a particular window, are actually less than the amount that the window was tested on.
Just to give you an idea, if you see a particular window that has a DP30 rating, which means the manufacturer is saying that that particular window can withstand 110 miles per hour wind. That particular window probably was tested by as much as 170 miles per hour wind, when they were trying to determine the pressure ratings.
If you live in Palm Beach County or any other South Florida area, then you know you have to take hurricane season very seriously and so do the building and government officials, this is why they have several requirements for approved ratings of impact windows. So there is an additional test that they require, which is to see how the impact resistant window will withstand flying debris, by using missiles to test the glass.